Shaking stress?

So as of recently, i noticed my whole body starts having little spazzems when ever my mother and brothers gf or my brother and mother go at it.Yelling screaming so on.

I don't really care when they do it, but when they do i start shaking, but idk why.Am i getting stressed out and not even know it?I do get sick to the stomach also.

I do have Ptsd.If that is to any help of it.

Other then that i cant even verbally get loud or i get the same result and my body stays like that for a hour or 2.

Im not sure if its normal or i should get it checked out.